php微信开发的时候 如何把access_token长期有效的保存，求高手解答
<?php
$appid="wx44a58ea3509d09fa";
$appsecret="d4624c36b6795d1d99dcf0547af5443d";
$url="https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid={$appid}&secret={$appsecret}";
//1、初始化CURL回话
$ch=curl_init();
//2、设置CURL选项
curl_setopt($ch, CURLOPT_URL, $url);
//将请求的结果以文件流的形式返回
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
//执行一个curl
$outopt=curl_exec($ch);
//4、关闭curl回话
curl_close($ch);
$access_token_arr=json_decode($outopt,true);
$access_token= $access_token_arr['access_token'];
echo $access_token;
?>
